In general, coloring matters such as phthalocyanine or its derivatives and the like are insoluble in water, and although they are soluble in organic solvents such as dimethylformamide (DMF), tetrahydrofuran (THF) and the like, their soluble amounts are small and the solubility is only several milligrams (mg).
Surfactants to make the phthalocyanine and the like soluble in water have heretofore been investigated, but no satisfactory surfactant has been developed. It is reported that functional group-substituted phthalocyanine derivatives can be dissolved in water to some extent by the use of sulfone-based surfactants. However, the solubility is not always sufficiently high and further unsubstituted phthalocyanine cannot be dissolved at all.
In connection with polymers insoluble in water, surfactants to make them soluble in water have been investigated in the same manner as described above. In fact, however, no satisfactory results have been obtained.
The present inventors have made extensive investigations to develop surfactants to make coloring matters such as phthalocyanine or its derivatives and the like, or water-insoluble polymers and the like, soluble in water.
In the course of study, it has been found that ferrocene derivatives are promising as surfactants having the aforementioned performance. As a result of further investigations based on the above findings, the present inventors have discovered that new ferrocene derivatives derived by introducing a specified substituent containing a polyoxyethylene chain or pyridinium ion, in ferrocene or its derivatives can achieve the object. At the same time, they have discovered that a water-insoluble (hydrophobic) organic thin film can be efficiently produced from various ferrocene derivatives including the new ferrocene derivatives by electrochemical techniques.
An object of the present invention is to provide novel ferrocene derivatives. Another object of the present invention is to provide surfactants having superior performance, containing the novel ferrocene derivatives. Another object of the present invention is to provide a process for efficiently producing thin films of hydrophobic organic substances.